The fastest G62s on our race planes were broken in by running a small diameter prop wide open for a few hours straight on petroleum based oil..Gets everything nice and loose...The winningest engine was raced for 5 years and was going strong until a crash demolished the plane....
Naturally, not all engines run the same..I ran 4 NIB G62s a while back on the same prop and fuel, one was 400 rpm better than the rest...Factory tolerances, ya know...